L2CAP doesn't seem to be up

Maksim Yevmenkin maksim.yevmenkin at gmail.com
Fri Mar 23 22:12:45 UTC 2007


On 3/23/07, ml-vic <ml-vic at de-martino.it> wrote:
> Maksim,
>
> Sorry for annoying you but actually I'm absolutely new to bluetooth with which
> I'm somewhat in deep waters.
>
> I read everything I found in freebsd docs and pieces of info and email but
> must admit not that much in man pages. This because an absolute beginner like
> me is frankly disorientated  by, e.g., this extracted from "man sdpd" :
>  ....................................................................................................
> The sdpd daemon keeps track of the Bluetooth services registered on the
>      host and responds to Service Discovery inquiries from the remote Blue-
>      tooth devices.
>      In order to use any service remote Bluetooth device need to send Service
>      Search and Service Attribute or Service Search Attribute request over
>      Bluetooth L2CAP connection on SDP PSM (0x0001). Etc.....
> ................................................................................
> ?????

from the handbook

28.4.7 Service Discovery Protocol (SDP)

The Service Discovery Protocol (SDP) provides the means for client
applications to discover the existence of services provided by server
applications as well as the attributes of those services. The
attributes of a service include the type or class of service offered
and the mechanism or protocol information needed to utilize the
service.

SDP involves communication between a SDP server and a SDP client. The
server maintains a list of service records that describe the
characteristics of services associated with the server. Each service
record contains information about a single service. A client may
retrieve information from a service record maintained by the SDP
server by issuing a SDP request. If the client, or an application
associated with the client, decides to use a service, it must open a
separate connection to the service provider in order to utilize the
service. SDP provides a mechanism for discovering services and their
attributes, but it does not provide a mechanism for utilizing those
services.

Normally, a SDP client searches for services based on some desired
characteristics of the services. However, there are times when it is
desirable to discover which types of services are described by an SDP
server's service records without any a priori information about the
services. This process of looking for any offered services is called
browsing.

===

specifically in your case, your nokia phone runs one or more bluetooth
server applications and provides bluetooth services. your pc is a
bluetooth client, who wishes to discover and possibly use one of the
provided services.

sdpd is only required if you want to run bluetooth services on your
pc. this way bluetooth service application (running on your pc) will
register itself with sdpd (running on your pc) so remote clients can
actually know that your pc is providing bluetooth services.

without doing anything at all, you should be able to discover
bluetooth services on your nokia phone, by simply

% sdpcontrol -a e61 browse

or

% sdpcontrol -a e16 search <service name>


thanks,
max


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